diff --git a/free-programming-books.md b/free-programming-books.md
index b3ea8da3f37123f8755bcaded69a7b0fb2a0d6d5..33ee73c5d20019ac69da78a0b203fe552032a740 100644
--- a/free-programming-books.md
+++ b/free-programming-books.md
@@ -520,7 +520,7 @@
 * [HTTP Succinctly, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/http) (PDF, Kindle) *(Just fill the fields with any values)*
 * [HTTP2 Explained](http://daniel.haxx.se/http2/) - Daniel Stenberg
 * [The TCP/IP Guide](http://www.tcpipguide.com/free/t_toc.htm)
-* [Understanding IP Addressing: Everything you ever wanted to know](https://web.archive.org/web/20080401000000*/http://www.3com.com/other/pdfs/infra/corpinfo/en_US/501302.pdf) (PDF)
+* [Understanding IP Addressing: Everything you ever wanted to know](http://pages.di.unipi.it/ricci/501302.pdf) (PDF)
 * [ZeroMQ Guide](http://zguide.zeromq.org/page%3Aall)
 
 
@@ -550,7 +550,7 @@
 * [Operating Systems: Three Easy Pieces](http://pages.cs.wisc.edu/~remzi/OSTEP/) (PDF)
 * [Practical File System Design: The Be File System](http://www.nobius.org/~dbg/practical-file-system-design.pdf) - Dominic Giampaolo (PDF)
 * [The Art of Unix Programming](http://catb.org/esr/writings/taoup/html/) - Eric S. Raymond
-* [The Design and Implementation of the Anykernel and Rump Kernels](https://github.com/rumpkernel/book) - Antti Kantee
+* [The Design and Implementation of the Anykernel and Rump Kernels](http://www.fixup.fi/misc/rumpkernel-book/) - Antti Kantee
 * [The little book about OS development](https://littleosbook.github.io) - Erik Helin, Adam Renberg
 * [The Little Book of Semaphores](http://greenteapress.com/semaphores/) - Allen B. Downey
 * [Think OS: A Brief Introduction to Operating Systems](http://www.greenteapress.com/thinkos/index.html) - Allen B. Downey (PDF)
@@ -663,7 +663,7 @@
 * [Introduction to Computing](http://www.computingbook.org)
 * [Introduction to Theory of Computation](http://cglab.ca/~michiel/TheoryOfComputation/) - Anil Maheshwari and Michiel Smid (PDF)
 * [Models of Computation](http://cs.brown.edu/people/jes/book/) - John E. Savage
-* [Practical Foundations for Programming Languages, Preview](http://www.cs.cmu.edu/~rwh/plbook/book.pdf) - Robert Harper (PDF)
+* [Practical Foundations for Programming Languages, Preview](https://www.cs.cmu.edu/~rwh/pfpl/2nded.pdf) - Robert Harper (PDF)
 * [Principles of Programming Languages](https://web.archive.org/web/20150418034451/http://www.cs.jhu.edu/~scott/pl/book/dist/) - Scott F. Smith
 * [Programming and Programming Languages](http://papl.cs.brown.edu/2014/index.html) - Shriram Krishnamurthi
 * [Programming in Martin-Löf's Type Theory](http://www.cse.chalmers.se/research/group/logic/book/) - Bengt Nordstroem
@@ -785,7 +785,7 @@
 * [BashGuide](http://mywiki.wooledge.org/BashGuide)
 * [Conquering the Command Line](http://conqueringthecommandline.com/book/frontmatter) - Mark Bates
 * [Getting Started with BASH](http://www.hypexr.org/bash_tutorial.php)
-* [Google Shell Style Guide](http://google-styleguide.googlecode.com/svn/trunk/shell.xml)
+* [Google Shell Style Guide](https://google.github.io/styleguide/shell.xml)
 * [Introduction to the Command Line](https://launchschool.com/books/command_line) - Launch School
 * [Linux Fundamentals](http://linux-training.be/linuxfun.pdf) - Paul Cobbaut (PDF)
 * [Linux Shell Scripting Tutorial - A Beginner's Handbook](http://www.freeos.com/guides/lsst/)
@@ -873,7 +873,7 @@
 ### Chapel
 
 * [Chapel Tutorial](http://faculty.knox.edu/dbunde/teaching/chapel/)
-* [Chapel Tutorial for Programmers](http://cs.colby.edu/kgburke/?resource=chapelTutorial)
+* [Chapel Tutorial for Programmers](http://web.archive.org/web/20150310075109/http://cs.colby.edu/kgburke/?resource=chapelTutorial)
 
 
 ### Cilk
@@ -904,7 +904,7 @@
 * [COBOL Programming Fundamental](http://yusman.staff.gunadarma.ac.id/Downloads/files/33460/COBOL_Programming_Fundamental.pdf) (PDF)
 * [Enterprise COBOL for z/OS documentation library](http://www-01.ibm.com/support/docview.wss?uid=swg27036733)
 * [Introduction to the COBOL Language](http://www-03.ibm.com/systems/z/education/skills_coursematerials.html#COBOL)
-* [OpenCOBOL 1.1 - Programmer's Guide](http://opencobol.add1tocobol.com/OpenCOBOL%20Programmers%20Guide.pdf) (PDF)
+* [OpenCOBOL 1.1 - Programmer's Guide](http://open-cobol.sourceforge.net/guides/OpenCOBOL%20Programmers%20Guide.pdf) (PDF)
 
 
 ### CoffeeScript
@@ -1158,7 +1158,7 @@
 * [Haxe and JavaScript](https://matthijskamstra.github.io/haxejs/) - Matthijs Kamstra (wikibook)
 * [Haxe Manual](http://haxe.org/documentation/introduction/) - Haxe Foundation (PDF, HTML)
 * [HaxeFlixel Handbook](http://haxeflixel.com/documentation/haxeflixel-handbook/) (HTML)
-* [Kha Handbook](http://wiki.ktxsoftware.com/wiki/Home)
+* [Kha Handbook](https://github.com/KTXSoftware/Kha/wiki/Tutorials)
 * [OpenFL Handbook](https://www.gitbook.com/book/openfl/openfl-documentation/details)
 
 
@@ -1172,7 +1172,7 @@
 * [Code Guide: Standards for developing flexible, durable, and sustainable HTML and CSS](http://mdo.github.io/code-guide/) - Mark Otto
 * [Dive Into HTML5](http://diveintohtml5.info) - Mark Pilgrim ([PDF](http://mislav.net/2011/10/dive-into-html5/))
 * [GA Dash](https://dash.generalassemb.ly)
-* [Google's HTML/CSS Style Guide](http://google-styleguide.googlecode.com/svn/trunk/htmlcssguide.xml)
+* [Google's HTML/CSS Style Guide](https://google.github.io/styleguide/htmlcssguide.xml)
 * [How to Code in HTML5 and CSS3](http://howtocodeinhtml.com)
 * [HTML Canvas Deep Dive](http://joshondesign.com/p/books/canvasdeepdive/toc.html) - Josh Marinacci
 * [HTML Dog Tutorials](http://www.htmldog.com)
@@ -1310,7 +1310,7 @@
 * [Developing Backbone.js Applications](http://addyosmani.github.io/backbone-fundamentals/) - Addy Osmani
 * [Eloquent JavaScript 2nd edition](http://eloquentjavascript.net) - Marijn Haverbeke
 * [Exploring ES6](http://exploringjs.com/es6/) - Dr. Axel Rauschmayer
-* [Google JavaScript Style Guide](https://github.com/google/styleguide/blob/gh-pages/javascriptguide.xml)
+* [Google JavaScript Style Guide](https://google.github.io/styleguide/javascriptguide.xml)
 * [Human Javascript](http://read.humanjavascript.com)
 * [JavaScript Allongé](https://leanpub.com/javascript-allonge/read) - Reginald Braithwaite
 * [JavaScript Bible](http://media.wiley.com/product_ancillary/28/07645334/DOWNLOAD/all.pdf) (PDF)
@@ -1437,7 +1437,7 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Common Lisp: An Interactive Approach](http://www.cse.buffalo.edu/~shapiro/Commonlisp/) - Stuart C. Shapiro
 * [Common Lisp Quick Reference](http://clqr.boundp.org)
 * [Common Lisp the Language, 2nd Edition](http://www.cs.cmu.edu/Groups/AI/html/cltl/mirrors.html)
-* [Google's Common Lisp Style Guide](http://google-styleguide.googlecode.com/svn/trunk/lispguide.xml)
+* [Google's Common Lisp Style Guide](https://google.github.io/styleguide/lispguide.xml)
 * [Interpreting LISP](http://www.civilized.com/files/lispbook.pdf) - Gary D. Knott (PDF)
 * [Learn Lisp The Hard Way](http://learnlispthehardway.org/book/) - Colin J.E. Lupton
 * [Let Over Lambda - 50 Years of Lisp](http://letoverlambda.com/index.cl/) - D. Hoyte
@@ -1672,8 +1672,8 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Practical PHP Testing](http://www.giorgiosironi.com/2009/12/practical-php-testing-is-here.html)
 * [Survive The Deep End: PHP Security](https://phpsecurity.readthedocs.org/en/latest/)
 * Symfony Framework
-  * [The Symfony Book 2.x](http://symfony.com/doc/2.8/book/)
-  * [The Symfony Book 3.x](http://symfony.com/doc/master/book/)
+  * [The Symfony Book 2.x](https://symfony.com/pdf/Symfony_book_2.8.pdf)
+  * [The Symfony Book 3.x](http://symfony.com/doc/current/index.html)
 * [Using Libsodium in PHP Projects](https://paragonie.com/book/pecl-libsodium)
 
 
@@ -1694,7 +1694,7 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 
 * [Creating HTML Reports in PowerShell](https://www.gitbook.com/book/devopscollective/creating-html-reports-in-powershell/details) (PDF,ePub,HTML)
 * [DevOps: The Ops Perspective](https://www.gitbook.com/book/devopscollective/devops-the-ops-perspective/details) (PDF, ePub, MOBI)
-* [Ditch Excel: Making Historical & Trend Reports in PowerShell](https://www.gitbook.com/book/devopscollective/ditch-excel-making-historical-trend-reports-in-po/details)(PDF, ePub, MOBI)
+* [Ditch Excel: Making Historical & Trend Reports in PowerShell](https://www.gitbook.com/book/devopscollective/ditch-excel-making-historical-trend-reports-in-po/details) (PDF, ePub, MOBI)
 * [Introduction to PowerShell for Unix People](https://www.gitbook.com/book/devopscollective/a-unix-person-s-guide-to-powershell/details) (PDF, ePub, HTML)
 * [Layman’s Guide to PowerShell 2.0 remoting](http://www.ravichaganti.com//blog/wp-content/uploads/2010/12/A%20layman's%20guide%20to%20PowerShell%202.0%20remoting-v2.pdf) (PDF)
 * [Mastering PowerShell](http://powershell.com/cs/login.aspx?ReturnUrl=%2fcs%2fblogs%2febook%2fdefault.aspx)
@@ -1763,7 +1763,7 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Dive into Python 3](http://getpython3.com/diveintopython3/) - Mark Pilgrim (3.0)
 * [Full Stack Python](http://www.fullstackpython.com)
 * [Google's Python Class](https://developers.google.com/edu/python/) (2.4 - 2.x)
-* [Google's Python Style Guide](https://github.com/google/styleguide)
+* [Google's Python Style Guide](https://google.github.io/styleguide/pyguide.html)
 * [Hacking Secret Cyphers with Python](http://inventwithpython.com/hacking/chapters/) - Al Sweigart (3.3)
 * [High Performance Python](http://ianozsvald.com/HighPerformancePythonfromTrainingatEuroPython2011_v0.2.pdf) (PDF)
 * [Hitchhiker's Guide to Python!](http://docs.python-guide.org/en/latest/) (2.6)
@@ -1778,7 +1778,7 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Learn Python in Y minutes](https://learnxinyminutes.com/docs/python/)
 * [Learn Python The Hard Way](http://learnpythonthehardway.org/book/) (2.5 - 2.6)
 * [Learn to Program Using Python](https://www.ida.liu.se/~732A47/literature/PythonBook.pdf) - Cody Jackson (PDF)
-* [Learning to Program](http://www.freenetpages.co.uk/hp/alan.gauld/) (2.3)
+* [Learning to Program](http://www.alan-g.me.uk/)
 * [Learning to Program with Python](http://python.cs.southern.edu/pythonbook/pythonbook.pdf) - Richard L. Halterman (PDF) (3.2)
 * [Lectures on scientific computing with python](https://github.com/jrjohansson/scientific-python-lectures) - J.R. Johansson (2.7)
 * [Making Games with Python & Pygame](http://inventwithpython.com/pygame/chapters/) - Al Sweigart (2.7)
@@ -1808,7 +1808,6 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Python Practice Projects](http://pythonpracticeprojects.com)
 * [Python Programming](https://upload.wikimedia.org/wikipedia/commons/9/91/Python_Programming.pdf) (PDF) (2.6)
 * [Python Scientific Lecture Notes](http://scipy-lectures.github.io)
-* [Python Scripting for Computational Science](http://info.baustatik.uni-due.de/Lehre/CM-AOS/Scripts/Abaqus/Python%20Scripting%20for%20Computational%20Science.pdf) - Hans Petter Langtangen (PDF)
 * [Python Standard Library](http://effbot.org/librarybook/) - Fredrik Lundh
 * [Snake Wrangling For Kids](http://www.briggs.net.nz/snake-wrangling-for-kids.html) (3.x)
 * [Test-Driven Web Development with Python](http://chimera.labs.oreilly.com/books/1234000000754/index.html) (3.3 - 3.x)
@@ -2097,7 +2096,7 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 ### Standard ML
 
 * [Programming in Standard ML '97](http://homepages.inf.ed.ac.uk/stg/NOTES/) - Stephen Gilmore, University of Edinburgh
-* [Programming in Standard ML, Draft](http://www.cs.cmu.edu/~rwh/smlbook/) - Robert Harper
+* [Programming in Standard ML, DRAFT](http://www.cs.cmu.edu/~rwh/isml/book.pdf) - Robert Harper
 
 
 ### Subversion